Preliminary studies indicate that adult rabbit and bovine vitreous contains an inhibitor of neovascularization. Further documentation of this inhibition will be done and extended to a comparison with other species. These will be tested in the beagle model of oxygen induced retinal neovascularization after preliminary testing in the more economical and simpler assays, such as tissue culture, corneal micropockets, and the chick chorioallantoic membrane (CAM).